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Electrics leakage/drain - 1937 TEN P2 Can anyone help?
Posted: Wed Apr 23, 2025 5:45 pm
by P27
We now have the petrol pump repaired, etc. and the engine running again - Hooray!
But it's still not driveable anywhere as there seems to be a drain on the battery when the ignition is OFF.
And even with the engine runnning, it still doesn't seem to be providing a positive charge to the battery. Even though the dynamo was checked/repaired some time ago (we believe).
Are there any contenders for where we should look first?
Is there anyone that could look at it for us? - we are in mid-Kent UK
Re: Electrics leakage/drain - 1937 TEN P2 Can anyone help?
Posted: Wed Apr 23, 2025 5:58 pm
by P27
The car is NEGATIVE earth. And the workshop manual seems to say it was built like that in 1937.
Is that right? (just checking)
Re: Electrics leakage/drain - 1937 TEN P2 Can anyone help?
Posted: Wed Apr 23, 2025 7:22 pm
by SHyslop
Absolutely positively , Positive !
Re: Electrics leakage/drain - 1937 TEN P2 Can anyone help?
Posted: Thu Apr 24, 2025 7:28 pm
by TonyG
Hi,
These cars were originally positive earth and this is shown in the workshop manual. As such, I’d suggest you check the diagrams again.
That said, it’s quite possible that it has been converted to negative earth at some point in the last 85 years!
I suggest you do some detective work, starting with the battery connections. To convert to neg earth I think I’m right in saying that the ammeter connections will need changing around for negative working or it will read the wrong way. The dynamo would need re-polarising but the connections stay the same so nothing there to give a clue. The coil connections also need swapping for neg earth but it will still run or, if you can find one, a neg earth coil with the correct windings will work even better.
It is possible, of course, that either you or a previous owner has connected the battery the wrong way round without making any of the other changes and, hence, the ammeter showing a discharge when it is actually charging or perhaps not charging because the dynamo isn’t functioning correctly. A volt meter across the battery will show if the voltage is rising with the engine running to indicate charging.
I converted both my 36/37 cars to negative earth and fitted neg earth Dynamators and neg earth SU electric fuel pumps at the same time. It’s a worthwhile modification but does stray from originality.
Tony.